Google should present you with a link to sign up for Google Apps here, and the option to connect it with your domain.

Check the video above for a walkthrough here, thanks to Amit Agarwal of Digital Inspiration. We've covered some alternatives if want to give up on Google, but let's be honest: it's difficult to find another web service with the same features and value as Google Apps. Give this workaround a try instead, and you'll get all of the benefits of Google Apps with the convenience of using your own domain (and one email address on that domain) with all of them.